1. Technical Field Embodiments of the present invention relate to a radar array antenna.
2. Description of the Related Art
A radar is a device that detects the distance and direction of a remote object or target and information on the surroundings of the target by sending beam signals to the target to receive and analyze the reflected waves.
A radar utilizes the linear directionality and reflective characteristics of radio waves, enabling detection unaffected by darkness, rain, snow, and other circumstances that may reduce visibility, and in recent times, radar devices are also being used in automotive vehicles for gathering various information.
While various types of antennas may be used for a radar antenna, one type of antenna commonly used is the array antenna having a microstrip patch.
The array antenna using a microstrip patch may include a main feed line and several branch lines that branch out from the main feed line, with a microstrip patch joined to each of the multiple branch lines.
FIG. 1 illustrates a microstrip patch radar antenna which uses multiple branch lines that branch out from a main feed line according to the related art.
Referring to FIG. 1, a microstrip patch radar antenna using branched lines according to the related art may include a main feed line 100, a multiple number of branch lines 102, and a multiple number of patch radiators 104, and the patch radar antenna illustrated in FIG. 1 can be formed on a dielectric substrate.
The main feed line 100 may be electromagnetically coupled with a feed point, so that a feed signal may be provided to the main feed line 100.
The feed signal provided to the main feed line may branch through the multiple branch lines 102 to be provided to the multiple patch radiators 104. The multiple branch lines 102 allow suitable amounts of power to be provided to the patch radiators 104, and the power provided from the main feed line 100 to each patch radiator 104 can be adjusted based on the width of the branch line 102.
In the case of a radar array antenna used for detection in a vehicle, etc., a polarization of +45 degrees or −45 degrees may be required, and the polarization of the radar array antenna may be determined by the angle in which the patch radiators are placed.
In a conventional radar array antenna, the joining may be implemented at a middle portion of one side of each patch radiator 104, similar to the feeding structure of a typical patch radiator. Also, to provide a polarization of +45 degrees or −45 degrees, the patch radiators may be placed at +45 degrees or −45 degrees with respect to the main feed line 100.
The branch line 102 that connects the main feed line 100 with the patch radiator 104 is one of the major causes of loss and preferably should have a minimized length. However, in the conventional radar array antenna, the branch line 102 is joined to a middle portion on one side of the patch radiator, and thus the length is not effectively minimized.